3-(4-chlorophenoxy) phthalide



United States Patent 2,802,832 3- 4enronormmoxmrurnmrnn Donald D.Wheeler and David C. Young, Midland, Mich., assignors to The DowChemical Company, Midiand, Mich., a corporation of Delaware No Drawing.Application April 30, 1956,

Serial No. 581,335

1 Claim. (Cl. 260-3433) This invention is directed to3-(4-chlorophenoxy) phthalide having the structure c it Phthalaldehydicacid is often represented in the literature as having the structure CHOCOOH

However, the acid employed in this invention and prepared as hereinafterdescribed exists almost entirely in the closed ring, 3-hydroxyphthalidestructure, as observed from a study of its infrared absorption spectrum.The infrared spectrum supports the closed ring3-(4-chlorophenoxy)phthalide structure for the product.

i atented Aug. 13, 1957 "ice In a method for carrying out the reaction,phthalaldehydic acid and 4-chlorophenol are heated in the temperaturerange from to 120 C. under reduced pressure for one to four hours.During the heating, a reaction occurs with the formation of the desired3-(4-chlorophenoxy)phthalide product and water of reaction. Much of thelatter is removed by volatilization during the heating process. Aftercompletion of the reaction, the crude product is poured into waterwhereupon the desired phthalide product precipitates as a solid. Thelatter is recovered by filtration. If desired, the product may bepurified by conventional procedures such as by recrystallization.

In a representative preparation, 59.3 grams (0.5 mole) of 4-chlorophenoland 75 grams (0.5 mole) of phthalaldehydic acid were heated to atemperature of C. at 10 millimeters pressure over a period of fourhours. At the end of this period the reaction mixture was poured intowater to obtain a solid 3(4-chlorophenoxy)phthalide product as aprecipitate. The aqueous mixture was filtered to recover theprecipitate. The latter was recrystallized from benzene to obtain apurified product melting at 157158 C.

The novel compound of the present invention is useful in controllingsoil-infesting fungi which attach germinating seeds. In a representativeoperation, inhibition of growth was obtained whenrosebengal-streptomycin agar was plated with an aqueous dispersion of3-(4- chlorophenoxy) phthalide containing the spores of Fusariumoxysporum lycopersici.

The phthalaldehydic acid employed in this invention may be prepared byfirst photochlorinating o-xylcne to obtaina,a,a,a',u-pentachloro-o-xylene by passing chlorine gas into o-xylenewhile illuminating with sun lamps. The resulting chlorinated o-xylene isthen heated with aqueous constant-boiling hydrochloric acid and ferricchloride solution, as more fully disclosed and claimed in the copendingapplication of James D. Head and Owen D. Ivins, Serial Number 279,682,filed March 31, 1952, now Patent No. 2,748,162.

We claim:

3-(4-chlorophenoxy)phthalide.

References Cited in the file of this patent UNITED STATES PATENTS2,150,595 Austin et a1. Mar. 14, 1939 FOREIGN PATENTS 523,595 CanadaApr. 3, 1956 OTHER REFERENCES Bistrzycki et al.: Berichte, vol. 27, pp.2632-40 (1894).

